HINT
ISOTOPES
WHAT IS AN ISOTOPE?
Atoms of the same element with different numbers of neutrons.
What has changed if there is a different number of neutrons. HINT: look at your periodic tables.
Something must have changed.
WHAT IS AN ISOTOPE
If you have a different number of neutrons, that means your atomic mass has changed.
Remember that atomic mass = neutrons + protons
THE NUMBER OF PROTONS NEVER CHANGES.
Why doesn’t this number ever change?
WHAT IS AN ISOTOPE?
If you change the number of protons you now have a different element.
EX: If you have an atom of Ne (Neon) with 11 protons now.. You actually would have an atom of Na
(Sodium)
CALCULATE THE FOLLOWING IN SODIUM
Protons
Neutrons
Electrons
CALCULATE THE FOLLOWING IN SODIUM
Protons 11
Neutrons 12
Electrons 11
Draw out the model
TWO SODIUM ATOMS
Sodium with 11 protons and 12 neutrons.
** This is what we see on the periodic table.
Sodium with 11 protons and 13 neutrons.
** Different from periodic table
Z
HOW DO WE SHOW ISOTOPES?
A: Mass Number
# protons + # neutrons in the nucleus
X
: element symbol
Always larger than Z
: Atomic number
#protons
A, X, and Z are very important to remember!
TRY IT IN YOUR NOTES
What is the element?
How many protons are in the element?
11
23
Na
What is the elements atomic mass?
TRY IT IN YOUR NOTES
What is the element?
Sodium
How many protons are in the element?
11
11
23
Na
What is the elements atomic mass?
23
TRY IT IN YOUR NOTES
What is the element?
How many protons are in the element?
17
33
Cl
What is the elements atomic mass?
TRY IT IN YOUR NOTES
What is the element?
Chlorine
How many protons are in the element?
17 17
33
Cl
What is the elements atomic mass?
33
TRY IT IN YOUR NOTES
An atom of
Nitrogen
7 protons
Mass number of 14
TRY IT IN YOUR NOTES
An atom of
Nitrogen
7 protons
7
14
N
Atomic mass of
14
HOW ELSE DO WE SHOW ISOTOPES?
Element
Name
Mass
Number
Sodium-23
** This is what we see on the periodic table
Questions,
Comments,
Concerns?
Please take out your whiteboards.
Write the isotope symbol for the chemical element that has 6 protons and 8 neutrons
(write the symbol both ways)
Write the isotope symbol for the chemical element that has 6 protons and 8 neutrons
(write the symbol both ways)
Carbon – 14
6
14
C
Write the isotope symbol for the chemical element that has 17 protons and 16 neutrons
Write the isotope symbol for the chemical element that has 17 protons and 16 neutrons
17
33 Cl or Chlorine-33
How many protons are in the isotope 54 Cr?
(Chromium-54)
How many protons are in the isotope 54 Cr?
(Chromium-54)
24 just like all Chromium
Protons NEVER CHANGE
TRUE/FALSE
Isotopes of an element always have the same number of neutrons.
A. False
B. True
TRUE/FALSE
Isotopes of an element always have the same number of neutrons.
A. False
TRUE/FALSE
Isotopes of an element always have the same number of protons.
A. False
B. True
TRUE/FALSE
Isotopes of an element always have the same number of protons.
B. True
Z = 9
A = 29
Draw the symbol.
How many protons?
How many neutrons?
